Strong international sales helped McDonald's Corp. post a 24 percent gain in first-quarter profit, but investors seemed nervous about the company's first monthly decline of U.S. same-store sales in five years.

Our video-game enemies are smart and getting smarter. The artificial intelligence that guides in-game characters today leads to far more natural actions and realistic friends and foes than in the past. "As graphics improvements top out, artificial intelligence will (drive) game innovation," says University of California-Santa Cruz professor Michael Mateas. A look at AI evolution:

McDonald's Corp. stock surged to an all-time high Thursday after the fast-food chain announced the largest dividend increase in its history and pledged to return more money to shareholders than Wall Street expected. The dollar's record low against the euro also boosted McDonald's, which has more than 6,000 restaurants in Europe.